On February 22, 2012, I gave a lecture at the House of Commons explaining the nature of the arguments for climate alarm, and offering my reasons for regarding the concern as being unjustifiably exaggerated. The slides of this lecture were widely circulated. Not surprisingly, the lecture led to a variety of complaints from those supporting alarm. The most thoughtful of these (by Hoskins, Mitchell, Palmer, Shine and Wolff) was a detailed critique posted at the website of the Grantham Institute that Hoskins heads. While there was a considerable amount of agreement between the critics and myself, the overall tenor of the critique suggested that I was presenting a misleading position. The following is my response to this critique. Since both the critique and my lecture focused on the science, the discussion is, of necessity, technical. Moreover, there are distinct limits to what can be covered in a one hour lecture. The following provides more detail than could be included in the lecture.

The critique by Hoskins et al. of a lecture that I recently gave seems to be primarily a statement of subjective disagreement, though it has important errors, and is highly misleading. The critics are, for the most part, scientists for whom I have considerable respect. The following response to their critique will, I hope, be considered to be part of a constructive exchange. Such constructive exchanges are new in the field of global warming, and, perhaps, represent a return to the normal process of scientific discourse.

There has been a large increase of atmospheric concentrations of carbon dioxide and other greenhouse gases due to emissions resulting from human activity over the past 150 years (although we do not agree that “equivalent CO2” concentration has yet doubled, as claimed by RSL on Slide 46 Global average surface temperature has very probably warmed by about 0.7oC in the same period (RSL Slide 10, or 0.8oC in Slide 4), ), Increasing carbon dioxide alone, and in the absence of climate feedbacks, should cause about 1oC warming for each doubling (RSL Slide 3).

We agree that scientific arguments should be based on physical reasoning and data, without exaggerating either the effects or our certainty (or uncertainty) about them. RSL is right to draw attention to uncertainties in climate change feedbacks e.g. associated with clouds. However, it is wrong to infer from this that we know nothing about these feedbacks. Contemporary science suggests unambiguously that there is a substantial risk that these feedbacks will lead to human-induced surface temperature change considerably larger than 1oC in global average this century and beyond.

» How much "Man Made" CO2 Is In The Earth's Atmosphere?
I think ALL of the CO2 in the Earth's Atmosphere is from man.
I'm not sure how much "Man Made" CO2 is in the Earth's Atmosphere.
There is .04% CO2 in the Earth's Atmosphere and of that "Man" has added an extra 4% (1 part in 62,500)